It is well known in the current art to build spatial light modulators (SLM) of a micro mirror type, e.g. U.S. Pat. Nos. 4,566,935, 4,710,732, 4,956,619. In general two main principles for building integrated devices, such as micro mirror SLM, have been employed.
An integrated circuit (IC) is manufactured to a finished state, and then the micro mirrors are manufactured on said IC. The micro mirrors are built onto the IC wafers. An advantage with this approach is that so called IC foundries can be used, which present a very cost efficient manufacturing of the electronics wafers. A disadvantage is that there is a very restricted selection of materials and methods that are usable for the manufacturing of the micro mirrors, because there is an upper temperature limit of about 400° C., above which the electronics will be damaged. This makes the manufacturing of micro mirrors having optimal performance more difficult.
Another way of building micro mirror SLM's is at the end of the process for making the IC, and micro mirror manufacture is started on the same wafers. The advantage with this approach is that there is a greater freedom of selecting materials, methods and temperatures for the manufacture of micro mirrors having good performance. A disadvantage is that the IC wafers cannot be manufactured in standard IC foundries. This is because IC wafers are subject to very strict demands on the process of manufacturing in terms of standardization in order to be able to maintain the quality in the process.
Therefore, there is a need in the art for an improved method for manufacturing micro electric/mechanical/optical integrated devices.